Ammunition having a subcalibre shell comprising a front cap and means for destroying this cap in flight



March 3, 1970 L. BIRKIGT 3,498,222

AMMUNITION HAVING A SUBCALIBRE SHELL COMPRISING A FRONT CAP AND MEANS FOR DESTROYING THIS CAP IN FLIGHT Filed Oct. 28, 1968 Z la United States Patent AMMUNITION HAVING A SUBCALIBRE SHELL COMPRISING A FRONT CAP AND MEANS FOR DESTROYING THIS CAP IN FLIGHT Louis Birkigt, Pregny, Geneva, Switzerland, assignor to Brevets Aero-Mecaniques S.A., Geneva, Switzerland Filed Oct. 28, 1968, Ser. No. 771,149 Claims priority, application Luxembourg, Nov. 3, 1967,

Int. Cl. F 42b 11/14 US. Cl. 102-52 6 Claims ABSTRACT OF THE DISCLOSURE The subcalibre shell comprises a front cap in the form of an ogive, which lengthens the ammunition. This front cap resists the shocks that the subcalibre shell undergoes during its travel through the barrel of the firing arm. The shell is equipped with a destructor device for destroying the front cap, but only after the shell has left the barrel, so that there will be no debris of the front cap in the barrel.

This invention relates to ammunition having a subcalibre shell, that is to say, in a general manner, to ammunition having a shell which presents a calibre smaller than the calibre of the ammunition considered; and the invention is more particularly, but not exclusively, concerned with ammunition in which the subcalibre shell is armour-piercing, and, in particular, with ammunition of this type whose subcalibre shell proper is engaged in a rear base (called sabot) adapted to accompany the shell at the beginning of the trajectory of this shell and then to separate itself from the shell.

It is known that ammunition having a subcalibre shell would present, in the absence of special measures, a length shorter than the length of ammunition of the same calibre having a normal shell.

This shorter length, of ammunition having a subcalibre shell, would consequently prevent its use in an arm provided with a feed device conceived for ammunition of the same calibre having a normal shell, that is to say for longer ammunition than the ammunition having a subcalibre shell.

In order to remedy this disadvantage, it has already been proposed to make ammunition having a subcalibre shell comprise a front cap in the form of an ogive compensating the subdimensionality in length of this ammunition, and accordingly permitting ammunition having a subcalibre shell to be obtained with the same length as ammunition of the same calibre having a normal shell; the cap is then arranged in a manner to be rapidly eliminated after the firing of the ammunition in a manner to bare the subcalibre shell and to render possible the flight behaviour provided for the shell, which behaviour would obviously be disturbed by the presence of the cap in question if this cap were not rapidly eliminated.

In order to permit this rapid elimination of such a front cap, it has been proposed to establish this cap such that it is sufficiently fragile to have a good chance of breaking under the effect of the shocks imposed on the subcalibre shell during its travel through the barrel of the firing arm.

This manner of proceeding, quite admissible when only armour-piercing ammunition is used during firing, becomes extremely dangerous if armour-piercing ammunition and explosive ammunition are used alternately dur ing firing (which is quite often the case), since the explosive ammunition then runs the risk of exploding at the interior of the barrel of the arm if it suddenly strikes, in this barrel, debris or fragments of front caps which belonged to previously fired ammunition having a subcalibre shell and having a front cap.

Patented Mar. 3, 1970 An object of this invention is precisely to remedy this danger, that is to say to permit the advantages that the presence of a front cap provides for ammunition having a subcalibre shell to be maintained, without the disadvantages presented by the front caps proposed hitherto, which were arranged in a manner to eliminate themselves by fragmentation in the barrel of the firing arm.

In ammunition of the type in question in which the subcalibre shell comprises a front cap in the form of an ogive whose presence brings the length of the ammunition (having a subcalibre shell) considered to the length of ammunition of the same calibre having a normal shell, according to the principal feature of the present invention, on the one hand, this front cap is arranged in a manner such that it is adapted to resist the shocks undergone by the subcalibre shell during its travel through the barrel of the firing arm, and on the other hand, this shell is equipped with a destructor device capable of assuring the destruction of the front cap, this destructor device being arranged in a manner to intervene only when the shell has just left the barrel of the firing arm, due to which one is assured of not finding, in any case, debris of the front cap at the interior of the barrel.

Other features of this invention will become apparent from the following description.

In any case, the invention will be well understood with the aid of the following complementary description, as well as of the accompanying drawings, which complementary description and drawings are, of course, given merely by Way of example.

In the drawings:

FIGURE 1 represents, in axial section, the sub-calibre armour-piercing shell of ammunition according to the invention; and

FIGURE 2 represents also in axial section a modification of the rear part of this shell.

The ammunition shown in the drawings can be, for instance, of small calibre (calibre comprised between 20 and 50 millimeters) and comprises a sub-calibre armourpiercing shell having a separable sabot.

This shell is constituted, as a whole, so that it comprises, among other elements, as shown in FIGURE 1, on the one hand, a core 1 constituted of a dense metallic material (for example tungsten carbide or sintered uranium U 238) and preferably arranged so as to comprise, from the rear towards the front, a principal cylindrical part 1 whose diameter D characterizes the subcalibre of the shell, a complementary cylindrical part 1 of smaller length and smaller diameter leaving a shoulder E at the front of the principal part 1,, and a point 1 which can be truncated, the core 1 being advantageously extended by an added nose-piece 2, for example of light metal, intended to improve the aerodynamic profile of the core, on the other hand, a sabot 3, preferably constituted of a light material such as an aluminum alloy, open towards the front, and in which the core 1 can fit with slight friction, that is to say with a possibility of sliding, the sabot 3, Whose diameter D corresponds to the calibre of the arm, carrying a rotating band 4 and having a circular groove 5 for the crimping of the cartridge case (not shown) intended to receive the propulsive charge of the ammunition, and furthermore, a locking device releasable during firing of the ammunition and intended to couple axially together, until the moment of release, the core 1 and the sabot 3, this locking device being advantageously constituted, in the case of a spinning projectile, by an expansible split ring 6 inserted between the shoulder E and the rear end of the added nose-piece 2, which expansible ring, after the firing of the ammunition, retracts, under the effect of the centrifugal force, into a groove 7 provided in the internal wall of the sabot 3 and defined, at the rear, by a shoulder F at the level of the shoulder E, thus releasing the core 1 in the axial direction.

And, with a view to bringing the length of this ammunition having a sub-calibre shell up to the length of ammunition of the same calibre having a normal shell, an ogival cap 8 of appropriate length and intended to be eliminated during firing of the ammunition is added at the front of the shell.

This being the case, according to the principal feature of the invention, on the one hand, the cap 8 is arranged, in particular in respect of its constituent material and its wall thickness, in a manner such that it is adapted to resist the shocks undergone by the shell during its travel through the barrel of the firing arm, these shocks being principally the lateral shocks resulting from the inevitable jiggling character of the movement of the shell in this initial phase of its trajectory, and on the other hand, this shell is equipped with a destructor device capable of ensuring the destruction of the cap 8, this destructor device being arranged in'a manner to intervene only when the shell has just left the barrel of the firing arm.

In this manner, one is assured that the destruction of the cap 8 will always take place at the exterior of the barrel of the arm, and that there will be consequently no risk of cap fragments remaining in the barrel, which might cause accidents (explosions at the interior of the barrel of the arm) in case of firing with explosive ammunition after firing with armour-piercing ammunition having a sub-calibre shell and a front cap.

With this in mind and with regard first of all to the cap 8, it can be advantageously constituted of thermohardenable plastic material, taking care to attribute to it a wall thickness sufficient for it to resist the shocks undergone by the shell during its travel in the barrel of the firing arm.

As for the destructor device which is to ensure the fragmentation and the elimination of the cap 8 once the shell has left the barrel of the arm, it is advantageously constituted by on the one hand, an explosive charge 9 capable, during firing, of ensuring the destruction of the cap 8, this charge 9 being advantageously disposed in a housing provided in the nose of the cap and open towards the rear; and on the other hand, firing means capable of ensuring the inflammation of the explosive charge 9, there means being then arranged in a manner to enter into action only when the shell has just left the barrel of the arm.

Then with regard to these firing means, they can advantageously be constituted: by making the front end of the nose-piece 2 of the armour-piercing shell carry a percussion point 10; and by taking advantage of the slowing down of the projectile, after it has left the barrel of the firing arm, in-order to cause, once the core of the shell is unlocked, a movement of advance of the core precipitating the percussion point 10 against the explosive charge 9.

Although it is not excluded to count solely on the deceleration of the projectile to project towards the front of core 1 and the percussion point 10 carried by the nose-piece 2 of this core, it seems preferable to provide additional propulsion means adapted to favour the advance of the core 1; these additional propulsion means can be constituted, for example, either as shown in FIG- URE 1, by a spring 11 interposed between the base of the sabot 3 and the rear end of the core 1, or again, as shown in FIGURE 2, when the core comprises at the rear a tracing composition 12, by a propulsive charge 13 housed at the rear of the sabot 3 in an annular space delimited by the internal wall of the sabot and by an added tubular casing 14, this annular space remaining masked by the rear end of the core 1 as long as this core remains in its rear position, whereas, when this core advances, once the projectile has left the barrel of the arm, the front opening of this annular space is unmasked,

which permits the firing of the propulsive charge 3 by the tracing composition 12 (ignited during the firing of the ammunition), this propulsive charge tending to propel the core 1 towards the front, thus re-enforcing the effect of the deceleration.

It is appropriate to note that, in order to favour the guiding of the core 1 during its movement of advance, a sleeve 15 added, for example, by screwing can advantageously be provided, in front of the sabot 3, the rear end of the sleeve 15 then defining the front of the groove 7 in which the locking ring 6 retracts after firing of the ammunition.

The operation of such a shell having a sub-calibre armour-piercing core is then the following:

As soon as the ammunition is fired, and as long as the acceleration of the projectile lasts in the barrel of the arm, the core 1, due to its inertia, bears towards the rear against the shoulder F by the intermediary of the locking ring 6 which is thus prevented from opening. This ring 6 opens only when this acceleration ceases, that is to say when the shell leaves the barrel of the arm; the opening of the locking ring 6 then axially releases the core 1 which, under the effect of the deceleration of the sabot combined with the effect of the additional propulsion means (spring 11 or propulsive charge 13), is precipitated towards the front and causes the percussion of the explosive charge 9 by the point 10; the explosion of the charge 9 causes the destruction of the cap 8, thus baring the front end of the sabot 3 which the aerodynamic forces then separate from the core 1, this core thus remaining free to follow alone its trajectory.

The present invention provides an armour-piercing shell having a sub-calibre core, which can be used in a firing arm equipped with a feed device conceived for ammunition having a normal shell (not a subcalibre shell), and the barrel of this firing arm does not risk, in any case, being more or less obstructed by the debris coming from the destruction of front caps of previously fired subcalibre projectiles.

Although this invention has been described with specific reference to two particular embodiments, the invention should not be limited thereto, since various modifications and changes are possible without departing from the spirit or scope of the invention.

What I claim is:

1. Ammunition having a sub-calibre shell, in which the sub-calibre shell comprises:

a core constituted of a dense material and whose diameter characterizes the sub-calibre of the shell,

a sabot open towards the front, constituted of a less dense material than the core, and in which the core fits with slight friction, that is to say with a possibility of sliding towards the front, the diameter of the sabot corresponding to the calibre of the firing arm,

a front cap, in the form of an ogive, whose presence increases the length of the ammunition, joined to the sabot, this front cap being adapted to resist the shocks which the sub-calibre shell undergoes during its travel through the barrel of the firing arm,

an explosive charge, housed in the front cap, for destroying the front cap,

a percussion point provided at the front of the slidable core, the housing of said explosive charge being open towards the rear to permit this precussion point to reach the explosive charge,

and a locking device, arranged to release with a slight delay after the firing of the ammunition, for coupling axially together, until the moment of release, the core and the sabot and for releasing, at the moment of release, the core from the sabot in order to permit the core to slide towards the front of the shell, whereby the percussion point ignites the explosive charge only when the shell has just left the barrel of the firing arm, in order to destroy the front cap 5 during the flight of the shell and so that there will be in no case any debris of the front cap at the interior of the barrel.

2. Ammunition according to claim 1, wherein said front cap is constituted of a thermohardenable plastic material and presents a wall thickness sufficient to resist the shocks which the shell undergoes during its travel in the barrel of the firing arm.

3. Ammunition according to claim 1, cornprising, in front of the sabot of its sub-calibre shell, a sleeve rigidly connected to said sabot and adapted to guide the core of the shell during the movement of advance of the core of said shell, the front cap of the shell being carried by said sleeve.

4. Ammunition according to claim 1, comprising additional propulsion means adapted to favour the advance of the core of the shell with respect to the front cap of said shell.

5. Ammunition according to claim 4, wherein said additional propulsion means are constituted by a spring interposed between the base of the sabot and the rear end of the core of the shell.

6. Ammunition according to claim 4, whose core comprises at the rear a tracing composition arranged to be ignited during the firing of the ammunition, wherein said additional propulsion means are constituted by a propulsive charge housed at the rear of the sabot in an annular References Cited UNITED STATES PATENTS 1,150,667 8/1915 Dunwoody 10252 3,181,465 5/1965 Anthony 10241 3,359,905 12/1967 Engel 102-93 3,374,740 3/1968 Voda 102-926 X FOREIGN PATENTS 453,955 6/1968 Switzerland.

SAMUEL FEINBERG, Primary Examiner CHARLES T. JORDAN, Assistant Examiner US. Cl. X.R. lO2-59, 60, 87 

